Semi-vaporisation burner



Nov. 8, 1960 F. G. M. FERRl SEMI-VAPORISATION BURNER 3 Sheets-Sheet 1Filed Jan. 28, 1958 I Nov. 8, 1960 F. e. M. FERRIE 6 SEMI-VAPORISATIONBURNER Filed Jan. 28. 1958 3 Sheets-Sheet 2 Nov. 8, 1960 F. G. M. FERRl2,959,006

SEMI-VAPORISATION BURNER F'iled Jan. 28, 1958 3 Sheets-Sheet 3 Zh enfif4/ Ji 1%; M M fia, MIMV United States Patent SEMI-VAPORISATION BURNERFranck Guillaume Michel Ferric, Cachan, France, as-

signor to Societe Nationale dEtude et de Construction de MoteursdAviation, a company of France Filed Jan. 28, 1958, Ser. No. 711,581

Claims priority, application France Feb. 1, 1957 Claims. (Cl. 60-3957)For improving the combustion in the chambers of jet propulsion units,notably for high-altitude and high-speed flight, it is necessary toprovide a mixture of air and fuel which is as homogeneous as possibleand to have a very stable pilot flame, in contact with which theignition of the air-fuel mixture is maintained.

The vaporisation of the fuel is very favourable, but it. cannot be fullyeffected by reason of the excessive rates. of flow which wouldnecessitate prohibitive vaporisation surfaces and a too considerableweight.

Consequently, the present invention has for its object to provide aburner device operating both with atomisation and vaporisation of thefuel. The said device comprises tubes, the Walls of which are adjacentto a flame zone, so that they are highly heated, and through which themixture of air and fuel to be vaporised flows. These tubes finallyconduct the said mixture into contact with a pilot flame maintained onthe downstream side of a screen, which protects it from the incidentflow.

Such a device, which is particularly applicable to annular combustionchambers, may be constructed in the form of a profiled'b'ody situated atthe inlet to the combustion chamber, which serves as a screen for thepilot flame, and on which tubes of appropriate cross-section and shapeare fixed in radial planes with a chosen spaced relationship, so as toobtain a good distribution of the air and to promote the exchanges offresh air and gas on the downstream side of the burner.

The description which follows with reference to the accompanyingdrawings, which are given by way of nonlimitative example, will enablethe manner in which the invention can be carried into effect to bereadily understood, the features appearing both from the drawings andfrom the text naturally forming part of the said invention.

Figure 1 is an axial sectional view of a first constructional form of aburner according to the invention for an annular combustion chamber.

Figure 2 is a view in the direction of the arrow X of Figure l, inwhich, however, the injectors 6 have been omitted for the sake ofclarity.

Figure 3 is an axial sectional view of another constructional form ofthe burner.

Figure 4 shows a further modified form.

In the construction according to Figures 1 and 2, the burner disposed atthe inlet to the annular chamber 1 (of which the axis is situated at thepoint at which the radial planes aa and b-b bounding Figure 1 meet)consists of a deflector ring 2 of V-shaped cross-section, of which thewider portion is directed downstream. Tubes 3 backwardly curved in suchmanner that their ends bear against the flanks of the section iron ofthe ring 2 are disposed in radial planes of the combustion chamber. Theradial portion of each of these tubes is formed with holes 4, which mayopen in the upstream and downstream directions as in Figure 1 or mayalso open in the upstream direction or laterally, or may bequincuncially formed, depending upon the result aimed at, withoutdeparting from the scope of the invention.

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The ring 2 is formed on the upstream side with holes 5, through whichthere passes a portion of the mixture of air and fuel, obtained byatomisation of the fuel on the upstream side of the burner through theorifices 7 in the injectors 6. When the combustion chamber is ignited,this carburetted mixture is ignited on the upstream side of the ring 2with the aid of a sparking plug or glow plug or any other device, andburns within the space 10 between the tubes 3. The flame thus obtainedconstitutes the pilot flame protected from the general flow by thescreen formed by the deflector ring 2.

A portion of the fuel atomised by the injectors 7, 8, 9 penetrates intothe tubes 3, which are also entered by the air coming from thecompressor, along the path indicated by the arrows.

The carburetted mixture flowing within the tubes 3 heated by the pilotflame is vaporised in contact with the hot walls of these tubes, passesthrough the holes 4, is ignited in contact with the pilot flame andburns with a very short flame, the vaporising tubes 3 performing thefunction of flame stabilisers. It will be seen that the burner comprisesin principle two successive flame traps. The first consists of thedeflector ring 2 and the second is a grid formed by the vaporisationtubes in themselves. It should be noted that the carburetted mixtureintroduced into each tube at 3 and 11 forms two opposed fluxes in theradial portion 12 of the tubes, whereby there is produced within thisportion an intense turbulent movement favourable to a good heat exchangewith the walls of the tubes.

The injectors may operate with double flow, the nozzles 8 and 9, forexample, providing the main flow, while the nozzles 7 provide the basicand starting flow. Owing to this arrangement, it is possible byappropriately choosing the positioning of the nozzles, to admit into thetubes only the quantity of fuel which is capable of being completelyvaporised. Although the design of this burner provides a very largevaporisation surface with minimum Weight, the quantity of fuel which canbe vaporised is limited. Consequently, the flow of fuel through thetubes (which varies with the positioning of the nozzles) must beadjusted to correspond to the maximum vapour production.

The fuel atomised at 8 and 9 has the whole length of the chamber inwhich to burn and its passage through the zone heated by the flame(which is maintained by the nozzles 7 and by the mixture vaporised inthe tubes 3) permits the vaporisation of the fuel droplets not burnt inthe first part of their travel.

In the modification of Figure 3, straight tubes 14 and 15 are welded inopposite pairs to the deflector ring 13 of V-shaped cross-section (whichhave any alternative aerodynamic form). A bank of fuel injector orifices18 feeds the pilot flame on the downstream side of the screen formed bythe ring 13. The said flame meets the tubes 14 and 15.

A portion of the carburetted mixture obtained by atomisation of fuel bythe sets of injector orifices 17 on the upstream side of the ring 13penetrates into the said tubes, in which it vaporises before beingdirected by the deflectors 16 welded to the tubes towards the center ofthe burner, where this mixture is ignited in contact with the pilotflame.

The modified form of Figure 4 is derived from the constructional form ofFigure 1, and comprises two additional annular deflectors 19 designedfor a better trapping of the flame in the primary zone. These defletcorsare formed with holes 20, through which the fuel mixed with the air canfeed the trailing zone formed on the downstream side of thesedeflectors. The more effectively protected flame passes between thetubes (as indicated by the arrows in the figure) and a more intenseheating of the said tubes and consequently a greater quantity of vapourare thus obtained. In addition, the fuel leaving the nozzles 9 and 8 isbetter canalised towards the tubes, the coefficient of filling of whichis improved and can be more readily adjusted. A number ofinterconnecting tubes 22 may be provided at intervals along theperiphery of the ring to facilitate the passage of the flame from thecentral deflector 2 to the deflectors 19. These tubes also promote theignition of the burner as a whole.

The said burner devices, which have been described as applied to annularcombustion chambers, may be adapted for tubular chambers with a numberof modifications.

These burners have the following advantages:

Good distribution of the return zones and of the direct air inletsarranged in successive sets;

Large heat exchange surface permitting a high fuel vapour productioncapacity.

Good cooling (by circulation of cold gas and vaporisation) of thematerial of which the burner is constructed, which has greaterresistance although situated in the hottest part of the chamber.

Increase in the period for which the mixture to be' vaporised remains inthe tubes.

The'combustion can take place in such manner that the atomised fuel,which requires a larger combustion space, burns before the chamber,while the vaporised fuel.

burns at the rear of the chamber, which is favourable to the output andassists in shortening the flame.

Readier combustion at low pressures, that is to say, athigh altitude.

What is claimed is:

1. In an annular combustion chamber bounded bytwo coaxial walls andsupplied with a high-velocity gaseous flow, a burner device comprising aplurality of arcuately spaced tubular systems extending in radial planesbetween said coaxial walls and at a distance therefrom, each tubularsystem being located entirely on one side of the axis of said annularcombustion chamber and comprising two radially spaced tubular sectionshaving front inlets facing upstream to collect fractions of said flowand rear means for diverting the collected fractions in a radialdirection, the tubular section farther from said axis diverting thecollected fraction towards said axis and the tubular section closer tosaid axis diverting the collected fraction away from said axis, wherebythe two collected fractions impinge on each other about half-way betweensaid diverting means and engage a central portion of the flow betweensaid tubular sections, first means for injecting fuel upstream of saidfront inlets of said tubular sections so that said tubular sectionscollect fuel as well as fractions of the high velocity gaseous fiow,second means for injecting fuel into said central portion, and means forholding a flame therein.

2. Burner device as claimed in claim 1, wherein the diverting meansconsists of oppositely directed bends at the rearmost part of thetubular sections of each system.

3. Burner device as claimed in claim 2, comprising a radial ported ductinterconnecting the oppositely directed ends of the tubular sections ofeach system.

4. Burner device as claimed in claim 3, wherein the ports in the ductpoint in directions radiating from the axis of said duct.

5. Burner device as claimed in claim 1, wherein the flame holding meanscomprise two coaxial, oppositely inclined, frusto-conical platesbounding a central annular divergent space, and wherein the tubularsystems are supported by said plates, the tubular sections" of saidsystems being fast with said plates and located on the outer sidethereof. with respect to said central space.

References Cited in the file of this patent UNITED STATES PATENTS2,548,087 Williams Apr. 10,1951 2,612,023 Morrison Sept. 30, 19522,635,426 Meschino Apr. 21, 1953 2,830,439 Johnson et al. Apr. 15, 1958

